It is widely known to use snowplows on all-terrain vehicles. FIG. 1 shows a conventional all-terrain vehicle 10 having a snowplow 12 attached to the chassis of the all-terrain vehicle 10. To drive the all-terrain vehicle 10, a driver sits on seat 14 and steers the vehicle 10 using a steering assembly 16. Chains 18 are often used on the rear wheels 20 of the all-terrain vehicle 10 to improve traction, which is usually needed so that the vehicle 10 can provide sufficient thrust for snowplowing.
The plow 12 shown in FIG. 1 has a straight, concave plow blade 22. Hinged adjustable V-blade plow systems that include a pair of plow blades connected along a vertical hinge are also quite common. Such a V-blade plow system is disclosed in U.S. Pat. No. 5,329,708 entitled "Universal Off Road Vehicle Snowplow" by Segorski et al., issued Jul. 19, 1994.
In either the straight blade plow shown in FIG. 1 or the V-blade plow shown in U.S. Pat. No. 5,329,708, the plow blade is mounted to the vehicle 10 using a heavy duty pivotable frame 24 that hangs underneath the chassis of the vehicle 10. The pivotable frame 24 attaches generally below the mid point of the vehicle 10 at pivot point 26. This configuration keeps the front end of the vehicle 10 from becoming too heavy to be practical for satisfactory operation. A mechanical operating lever 28 is provided to lift the blade 22 off of the ground 30 by rotating the blade 22 about pivot point 26 generally in the direction of arrow 32. The mechanical operating lever 28 is located so that a driver sitting on the seat 14 of the vehicle 10 can access the mechanical lever 28 by leaning forward. Partly due to the amount of room available for the plow frame 24, and partly due to cant incurred by the plow blade 22, the plow blade 22 cannot typically be raised more than 2 or 3 inches off of the ground when the plow blade 22 is lifted in the direction of arrow 32.
It is normally desirable that a bottom cutting edge 33 of the plow blade 22 be aligned or flush with the ground surface 30 when plowing. A trip mechanism is often provided to allow the plow blade 22 to pivot about pivot point 34 against the force of spring 36 upon encountering an obstacle. Above referenced U.S. Pat. No. 5,329,708 discloses a trip mechanism for a V-plow system. However, with the trip mechanism in U.S. Pat. No. 5,329,708, the height of the plow blade when it is in the full-down position cannot be adjusted.
The plow systems shown in FIG. 1 and shown in U.S. Pat. No. 5,329,708 have several drawbacks. First, the systems are manually operated and many plow users lack the strength, energy or desire to manipulate the plow blade. In addition, the systems are generally difficult to mount and remove from the all-terrain vehicle. Thus, most users mount the plow to the all-terrain vehicle at the beginning of the winter plow season and do not remove the plow until the end of the winter plow season. With the plow installed, the vehicle 10 is virtually useless as an all-terrain vehicle. There is very little clearance under the bottom cutting edge of the plow blade even when the blade is completely lifted. There is also very little clearance under the chassis of the vehicle 10 due to the frame 24. Further, the weight of the plow substantially alters the maneuverability of the all-terrain vehicle 10.
Another drawback of these systems is that many all-terrain vehicles are relatively light (e.g., lighter all-terrain vehicles range from about 450 lbs. to 600 lbs. in total weight not including the weight of the plow), and therefore all-terrain vehicles are often underpowered for moving large quantities of snow.
Another disadvantage with the V-plow systems such as shown in U.S. Pat. No. 5,329,708 is that it is difficult to maintain the bottom cutting edge of the plow blade flush with the ground surface unless the plow 12 is precisely mounted on the vehicle 10, and the plow blades 22 are accurately positioned to align the bottom cutting edge flush with the ground. If one wishes to apply down pressure from the V-plow onto the ground, the bottom cutting edge of the V-plow does not in general remain flush with the ground surface when rotated downward. Thus, it is difficult or even impossible to provide evenly distributed down pressure.